WorkshopSummary:RickettsialDiseases:Host-Vector-PathogenInteractions Rickettsialdiseasesaresignificantcausesofmorbidityandmortality.Theyareresponsibleforthemajorityof hospitaladmissions,intensivecareadmissions,andfatalitiesamongalltick-borneinfections.Manyareemerging orre-emerging,havebiothreatimplications,and/orareneglected.Rickettsialdiseaseshavebeenresponsible forthelossofmillionsoflivesandweresecondonlytomalariaasthecauseoffebrileillnessamongtroopsin WorldWarII,theKoreanWar,andtheVietnamConflict.Novaccineforanyrickettsialdiseaseexists,andthe interactionsofthesebacteriawiththeirarthropodvectorsandmammalianhostsarepoorlydefined.Fillingsuch knowledge gaps will improve understanding of rickettsial pathobiology and promote development of novel treatments.Indeed,the2011InstituteofMedicineoftheNationalAcademiesworkshopreport,?Criticalneeds and gaps in understanding, prevention, amelioration, and resolution of Lyme and other tick-borne diseases? emphasizedthatunderstandingthesepathogens?factorsthatenablethemtosurviveandcausediseasewould lead to development of novel countermeasures. The complexity of the challenge of preventing rickettsial diseasesisdue,atleastinpart,totheevolutionaryrelationshipsbetweentheetiologicagents,theirarthropod vectors,andmammalianhosts.TheAmericanSocietyforRickettsiology(ASR)hasalonghistoryofproviding forums that foster scientific interactions and rich intellectual exchange among world-renowned experts on rickettsial diseases. The 28th Meeting of the ASR will be held June 11-14, 2016 in Big Sky, Montana. Approximately200attendeesrepresentingjuniorandestablishedscientistsfromacademia,government,and industryareanticipated.Theconference?soverarchinggoalistoadvanceknowledgeandstimulateinteractions among these researchers through lectures, short oral presentations, poster sessions, and networking opportunities. To address the aforementioned knowledge gap, we propose a small workshop within the framework of the 28th meeting entitled, ?Rickettsial Diseases: Host-Vector-Pathogen Interactions.? The workshop?saimsareto(i)provideaforumthatpromotesscientificexchangeamongparticipantsandexperts throughinvitedkeynoteandplenarylectures,shorttalks,andpostersbyleadersandjuniorinvestigatorsthat study rickettsial and other vector-borne diseases;? (ii) offer a program that presents the latest, cutting-edge research of rickettsial and other diseases caused by arthropod-borne/obligate intracellular pathogens;? (iii) provide a venue that fosters intellectual exchange and networking opportunities between junior and senior investigators;?and(iv)promoteparticipationbythosethatareearlyintheircareersandthatareunderrepresented inthebiomedicalsciences,includingwomen.Effortswillalsobemadetoaccommodateattendeesinneedof childcare.Supportfortheworkshopisrequestedtocoverthecostofcoordination,facilities,travelexpensesfor invitedspeakersandselectedattendees,andforaudio-visualservicesandprogramproduction.